Transmission identification

[C101971]

I've got a 1971 gmc c15 with a 350 mated to a 4 speed. I've got a general idea of which tranny it is by the style of the shifter and the location of it is very close to the fire wall. I can't tell for sure without cutting out the floor or dropping the tranny, which I would like to avoid doing. I'm pretty sure it's either a Muncie sn420 or a sn465.

Reason I need to know is I want a Hurst shifter and I want to order the right part, also if I have to cut the floor I would like to avoid making any un necessary cuts.

There is also the chance that I have the complete wrong idea of what trans it is but there was only so many that are mounted that close to the fire wall and are a 4 speed.

Long question short, where is there an easy to see number to identify the transmission?

[C101971]

These are the best pictures I can find of the trans

[geezer#99]

Good news, bad News!
The way to tell a sm420 compared to a sm465 is wherereverse is. Thesm420 is to the left and down, the sm465 is to the right and down.
Bad news is there is no hurst shifter for either one.

If you want a Muncie m20, 21 or 22 you need a tranny with a side cover shift arms.

[B. W.]

Hard to tell from the pic but the top cover looks like a 465.

[LockDoc]

Originally Posted by C101971

I've got a 1971 gmc c15 with a 350 mated to a 4 speed. I've got a general idea of which tranny it is by the style of the shifter and the location of it is very close to the fire wall. I can't tell for sure without cutting out the floor or dropping the tranny, which I would like to avoid doing. I'm pretty sure it's either a Muncie sn420 or a sn465.

Reason I need to know is I want a Hurst shifter and I want to order the right part, also if I have to cut the floor I would like to avoid making any un necessary cuts.

There is also the chance that I have the complete wrong idea of what trans it is but there was only so many that are mounted that close to the fire wall and are a 4 speed.

Long question short, where is there an easy to see number to identify the transmission?

Check out this picture. You should be able to tell by the shifter tower....

LockDoc

[C101971]

Originally Posted by geezer#99

Good news, bad News!
The way to tell a sm420 compared to a sm465 is wherereverse is. Thesm420 is to the left and down, the sm465 is to the right and down.
Bad news is there is no hurst shifter for either one.

If you want a Muncie m20, 21 or 22 you need a tranny with a side cover shift arms.

Well ****, is there any shifter kit made for them? Mine shifts great but so much play in every gear.

[LockDoc]

Originally Posted by C101971

Well ****, is there any shifter kit made for them? Mine shifts great but so much play in every gear.

What do you mean by play? Side to side or front to back?

LockDoc

[kwmech]

By the looks of the pic and the year, I'd say a 465. Should also have 2 pto covers. The 420 has 1 cover. What automatic was in there before?

[geezer#99]

[QUOTE=C101971;8354815]Well ****, is there any shifter kit made for them? Mine shifts great but so much play in every gear.[/QUOTE

No hurst shifters. None!
I bet that’s gotta be pretty cold on the feet driving in the temps you’re getting now!

[C101971]

Originally Posted by LockDoc

What do you mean by play? Side to side or front to back?

LockDoc

Like a hotdog down a hallway in neutral and about 3 inches of play in gear. If I go over a bump I can literally see the shifter bouncing all over the place, while in gear.

[C101971]

Originally Posted by kwmech

By the looks of the pic and the year, I'd say a 465. Should also have 2 pto covers. The 420 has 1 cover. What automatic was in there before?

Was originally an auto yes, bought it as a manual swap

[C101971]

[quote=geezer#99;8354962]

Originally Posted by C101971

Well ****, is there any shifter kit made for them? Mine shifts great but so much play in every gear.[/QUOTE

No hurst shifters. None!
I bet that’s gotta be pretty cold on the feet driving in the temps you’re getting now!

She is safe in a warm garage now hahaha. Damn, was hoping there was a short shifter of some sort.

[geezer#99]

Originally Posted by C101971

Like a hotdog down a hallway in neutral and about 3 inches of play in gear. If I go over a bump I can literally see the shifter bouncing all over the place, while in gear.

That kind of movement is caused by motor or tranny mounts being bad. Being as how it was converted you better check them closely.

[LockDoc]

Originally Posted by geezer#99

That kind of movement is caused by motor or tranny mounts being bad. Being as how it was converted you better check them closely.

That, or one of the two pivot pins is missing in the tower. If I remember correctly there are two locator or pivot pins on the ball that sits just inside the tower. One or both of those could be missing. I'm sure that could cause what you are seeing.....

LockDoc

[C101971]

Originally Posted by LockDoc

That, or one of the two pivot pins is missing in the tower. If I remember correctly there are two locator or pivot pins on the ball that sits just inside the tower. One or both of those could be missing. I'm sure that could cause what you are seeing.....

LockDoc

I've heard that is a common issue, replaced the shifter a few months ago and it seemed fine, tac welds we're good. But on the other hand the guy who I bought it off of could have just re tac welded it and called it a day. I have a few other shifters kicking around so I will try a few different methods of trying to stiffen it up